At least six Africans trying to migrate to Europe died and an estimated 30 were missing in the Mediterranean Sea after their boat sank off the coast of Tunisia on Thursday, according to Tunisia’s Defense Ministry.

Tunisian naval and coast guard forces retrieved the bodies, rescued 34 survivors and are searching for the people listed as missing, the ministry said in a statement. The survivors told rescuers that the boat had 70 people on it and they were headed for Italy, the ministry said.

The boat had left from neighboring Libya and sank about 40 kilometers (24 miles) off the Tunisian town of Zarzis, near the Libyan border, it said.

The survivors included people from Egypt, Sudan and Ivory Coast, according to Mongi Slim, head of the Tunisian Red Crescent.

It’s the latest of several migrant boat sinkings in the region. The central Mediterranean route, which runs from North Africa to southern Italy, is the busiest and deadliest migration route to Europe. People travel from Libya and Tunisia in crowded boats and at the mercy of the smugglers they pay to get them across the sea.

About 60,000 people arrived in Italy by sea last year, and some 1,200 died or disappeared on the journey, according to the United Nations refugee agency.

The Tunisian Defense Ministry said authorities thwarted eight boat migration trips in the last 48 hours off the coast of the city of Sfax, and 130 people from Tunisia and sub-Saharan Africa were detained.